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Our app's nearly finished. We just want to provide some sort of notification to the user if no photos match

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their search query.

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Now the class that provides the data to the recycler view for displaying, is our flickr recycler view

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adapter class.

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Now that's the easiest place to add a notification if there's nothing to display.

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So let's open up that class.

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Now the data's provided to the recycler view when it calls the onBindViewHolder function.

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So all we have to do is check the list of photos and provide a suitably formatted holder

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if there's nothing to display. Let's go ahead and do that, so on bind view holder.

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So what we're going to do is add some code here at the start.

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We're going to put if parentheses photoList.isEmpty closing parentheses and open a codeblock, and I'm

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going to do a holder dot thumbnail dot setImageResource parentheses. And it's going to be R dot

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drawerable.placeholder, and then we're going to put holder.title.text equals, in two double quotes, No photos

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match your criteria,

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or match your search is probably easier to understand.

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Full stop backslash n backslash n Use the search icon to search for photos.

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Then what we're going to do is change this at the end of the code block, code block and I'm going to put an else, and then another code block.

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Then we're going to put the rest of the code up to, but not including, that final line of the holder dot title

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dot text. We can put all this code in that code block. Paste it in there like so.

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So basically that's now only going to be executed on the else.

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So we're testing the photos first, and if it's null or contains no photos, we set the image to the placeholder

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image and provide an informative message in the photo's

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title text view. But if there is data we just execute the same code as before.

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Now the set image resource function that I'm calling here on line 43, that loads the placeholder

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image from the resources and puts it into the image view.

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Now these backslash n characters, slash n slash n characters, they represent line breaks, and they're

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a simple way to format text.

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So Kotlin will replace the backslash n with a newline character when the text is displayed.

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Now we've got this warning over here about a hardcoded string,

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and we really should put that into a string resource.

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And as we saw in a previous video, Android Studio does make that very easy for us.

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So I'm just going to click on the text, like so, and do alt enter. Then I can come over here and use the lightbulb.

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Now we saw that working earlier but at the moment it's not working here.

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Now that's annoying but it's possibly not a bad thing.

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Over-reliance on the code generators can lead to us not understanding the code, and it is useful to be

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able to do things without using the code generator.

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And yes I'm trying to be positive about this.

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Sometimes things just don't work until Google releases a fix.

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Now I may be trying to be positive about this problem, but don't think I'm making light of it.

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When you're learning about all this, it can be very hard to work out if you're doing something wrong.

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Most of the time you will be doing something wrong.

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Bugs like this are actually quite rare, but when they do happen they can be very frustrating.

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Now one thing that may help is to focus on what you're really trying to achieve.

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Are we trying to get Android Studio to create a string resource for us, or do we just want to use a

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string resource. So it would be nice if Android Studio did it for us,

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but that's not our aim here.

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Our aim is to remove those warnings and get the text into a resource.

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So I'm not going to fight the tool here. We'll end up getting frustrated.

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Instead what I'm going to do is cut the text out of the code, leaving the speech marks, like

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so. Then I'm going to go to my strings.xml file, which is in our res folder and then the value

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subfolder.

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Double click on that.

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We're going to add it right at the end here, and we're going to put, open a string tag, so string name equals,

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and we'll call it empty underscore

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photo, close the tag and I'm going to paste in the string, and you saw that pasting in text that contains

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line breaks doesn't always work too well.

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So if you get the text split over several lines as I have, then just remove those extra lines.

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Basically just delete the line breaks and type in the slash in manually. So I'm going to go ahead and do that

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and put in my two backslash n's there like so, and we're good to go there.

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Now the next thing is to change the code to use the resource.

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So go back to our flickr recycler view adapter and to our onBindViewHolder method.

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So we want to change this code now to use the resource.

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Now we can't do that by signing directly to the text property, but we can pass a resource ID to the set

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text function, and that's easier than trying to get a resource object and extracting the string from

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the resources. Now that worked fine in an activity, but isn't so easy in our adapter class. So I'm going to type, inside

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the double quotes, holder dot

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title. We can't use dot text, we use dot setText, parentheses R.string.empty underscore

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photo.

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So even without Android Studio's help that wasn't too hard.

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There's really no excuse for hardcoding strings in your code.

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That's the bottom line.

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Alright so that should work, but the recycler view calls the getItemCount function to check if there's

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any data to display, and it does that a lot.

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So often in fact, that we commented out the logging in that function to keep the log cat a bit tidier.

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This is the getItemCount, you can see that we've commented out the logging.

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Now if there's no data, getItemCount will return 0,

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and the recycler view won't attempt to display anything.

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So we have to get our adapter to fib and tell he recycler view that there is at least one data item for it

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to display.

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Now the recycler view won't know or care that it's not a real flickr photo.

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It'll just know that there's one item, and will go ahead and display it.

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So let's actually add some code for that.

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So on this line here,

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all we're going to do is change the 0 to a 1.

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So now if no photos match the tags that we search for, we get the placeholder image and a message.

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Now that previous search for the Porsche driving monkeys should still be saved.

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So let's run the app and see what happens.

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So as you can see when I run the app, there still aren't any, and we're now getting this message and the placeholder

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image.

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So that's a better user experience than the blank screen we had before,

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and it's actually well worth the extra effort to code it.

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Alright so that's the end of this section.

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00:07:07,470 --> 00:07:09,710
So we've covered a lot of ground in this section.

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We had to look at a different way to use async tasks to download data from the internet, then parse the json

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data rather than the xml that we used in the top 10 downloader app.

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Now the downloading and parsing involved using callback functions to notify the calling process that data

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was available.

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Now in the process,

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we created our own interfaces for classes to implement, so that they could reliably provide callback

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functions to the async classes.

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And then we looked at using the recycler view, and recvcler view adapter classes, to display the data in

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a scrolling list on the device.

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And in order to view the photos at a larger size,

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we had to use a gesture detector to work out what kind of input we were getting from the user.

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And we responded to taps and long presses, while still allowing scroll events to be handled by the system.

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We then had a good look at material design, before using it to style our flickr browser app,

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along material design lines. Now in order to do that we had to learn about themes and styles,

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and keeping a consistent look across different versions of Android.

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And we finished off by looking at using string resources, rather than hardcoding text into our code

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and layouts.

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And finally we added a search feature to the app so that we could download different photos by specifying

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different tags to select them.

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So again that's the end of this section.

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I'll see you in the next one.